The 4th Infantry Division is a division of the United States Army based at Fort Carson, Colorado. It is composed of a Headquarters and Headquarters Battalion, three brigade combat teams (1st Stryker BCT, 2nd Infantry BCT, and 3rd Armored BCT), a Combat Aviation Brigade, the 4th Infantry Division Sustainment Brigade, and a Division Artillery.

The 4th Infantry Division's official nickname, "Ivy", is a play on words of the Roman numeral IV or 4. Ivy leaves symbolize tenacity and fidelity which is the basis of the division's motto: "Steadfast and Loyal." The second nickname, "Iron Horse," has been adopted to underscore the speed and power of the division and its soldiers.

More Info: en.wikipedia.org